Under normal operating and storage conditions lubricants are subject to high temperatures and oxygen which leads to oxidation and decomposition of the lubricants. Oxidation of a lubricant can lead to the build-up of oil-soluble acids, lacquers and sludge which will cause serious damage to engines and other lubricated systems. Typically, antioxidant additives are blended with lubricants in order to improve the stability of the lubricants and thereby enhance the ability of the oil to resist oxidation.
Mechanical systems under heavy loads will deteriorate due to the frictional forces created by relatively moving, rubbing and bearing metal surfaces. Often, lubricants for such operations cannot prevent wear of the metal nor reduce the coefficient of friction and as a result the system performance is affected. Often, antiwear additives load carrying and friction modifying additives are blended with lubricants in order to prevent wear, reduce fuel consumption and increase the operating life of the machinery.
The metal salts of diorganodithiocarbamic acids have been described as multifunctional, antioxidant, antiwear and corrosion inhibiting additives for lubricants. However, these additives pose toxicological risks, thus, efforts are made to replace the metal salts with equally effective metal/phosphorus-free diorganodithiocarbamates.
The reaction products of diorganodithiocarbamic acids and alkylthiosulfinyl halides have been described as antioxidants and antiwear additives in lubricant compositions in U.S. Pat. No. 4,859,356 issued to Okorodudu.